I already mentioned that there are edge cases. Edge cases do not discredit foundational frameworks that define reality.

But when you are trying to define or classify things it is the edge cases that are key. It is at the edges that we hope to find a clear divide between one set of things and another.

Unfortunately, with sex chromosomes, their impact on development and that effect on performance it feels like the more we know the less we understand.

International sporting bodies have huge resources and access to the best experts in the various fields and they can’t come up with a good way to classify male and female. I could, at least, see the logic in their going for testosterone exposure during puberty as being a useful guide, although it is complex and rather arbitrary, but there are counter-arguments to that which suggest it isn’t useful. So the sporting bodies seem to be falling back on chromosome testing, which is no guide at all to performance and seems to be favoured because it is easy to test for - like the drunk looking for his keys under a lamppost because the light was better there.